The present invention relates to a series of new pyrroloquinoline derivatives which have valuable fungicidal activities which make them of considerable value in agriculture and horticulture. It also provides methods and compositions using the compounds of the present invention as well as processes for their preparation.
The compounds of the present invention have the following basic molecular structure: ##STR2## Certain compounds having a similar structure are known and are described in Japanese Patent Publication (Kokoku) No. Sho 52-48176 (equivalent to U.S. Pat. Nos. 3,917,838 and 4,008,325), J. Agric. Food Chem., Vol. 29, No. 3,576-579 (1981) and Japanese Unexamined Patent Publication (Kokai) No. Sho 54-163813.
The compounds of the present invention are characterised by a substituent at the 7-position of the above-mentioned basic structure.
Japanese Unexamined Patent Publication (Kokai) No. Sho 54-163813 discloses the compound of formula: ##STR3## that is, with a methyl group at the 6-position and no substituent at the 7-position.
Although the disclosures of certain of the other prior art embraces the compounds of the present invention, as well as a class of superficially similar but unrelated compounds having a carbonyl group at the 2-position instead of the 4-position, there is no disclosure of the limited class of compounds claimed herein.
When compounds having fungicidal activities are used in practice as agricultural chemicals, it is generally considered highly desirable that they should be capable of exhibiting their activities when used in relatively small amounts. It is also necessary that they should be free from phytotoxicity. Further, in recent years, labor-saving has become of greater importance in the treatment of crops and greater emphasis has been put on the safety of workers. For these purposes, compounds having systemic (osmosis migration) characteristics are particularly advantageous.
We have now surprisingly discovered that a limited series of compounds having the above-mentioned basic structure and having a substituent at the 7-position have excellent fungicidal activity for use in agriculture and horticulture, and have good systemic (osmosis migration) characteristics without any phytotoxicity, unlike the prior art compounds referred to above.